In many communications applications, such as avionics networks, it is desirable to use optical signals to communicate signals between nodes of the network. Optical communications may provide a lighter alternative to electronic communications, may provide higher resistance to electromagnetic interference (EMI) and background noise, and may provide higher communication speeds.
Some communications networks may use wavelength division multiplexing (WDM) whereby different nodes of the network are allocated different wavelengths at which they transmit optical signals. In some applications, different nodes may transmit signals at different frequencies along the same optical communications path, such as a common optical fibre.
In some critical applications, such as aircraft avionics networks, each type of node that is to be used in the network must pass rigorous testing. Such testing may involve significant costs and so it may be desirable to reduce the number of types of node that must undergo such testing.
Furthermore, in some network topologies it is desirable for signals transmitted by a node to be removed from the network when the signals are no longer required. Such removal can be computationally intensive and may require active optical devices that can be complex and costly to test, and may lead to latency as data is read and retransmitted from one node to another.